Fuel-supply structure



AQW. POPE, JR

FUEL SUPPLY STRUCTURE Filed July 21, 1926 By @ww,

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March 24, 1931.

Patented Mar. 24, 1931 UNITED STATES,

ARTHUR W. POPE, JR., OF WAUKESHA, WISCONSIN, ASSIGNOR TO WAUKESHA MOTOR-PATENT OFFICE COMPANY, OF WAUKESHA, WISCONSIN, A. CORPORATION OFWISCONSIN FUEL-SUPPLY STRUCTURE Application filed Ju1y 21, 1926. SerialNo. 123,967.

My invention relates to fuel supply structure for fuel supply systems inwhich the internal combustion engine draws its fuel directly from thefuel tank. In such systems,

compensation must be made for any change in level of the fuel in themain fuel tank as otherwise a richer mixture will be delivered to theengine when the tank is full than when it is empty. The object of theinvention is to provide structure and arrangement which will cause theengine to draw its fuel from the tank under a pressure which issubstantially always that at the bottom of the tank.

Referring to the drawing, the figure is a cross sectional view of a fueltank and a carburetor structure in association therewith.

The fuel tank 1 is below the level of the carburetor C. The fuel pipe 2extends from the bottom of the tank and to the carburetor to dischargefuel into the Venturi tube 3, which is located in the air passagewaythru the carburetor. A suction duct 4 extends from the tank above thefuel level therein to the carburetor or to the intake passageway to theengine. As shown, it connects with the carburetor air passageway betweenthe Venturi tube 3 and the throttle valve 5 so that when the throttlevalve is open, the duct and consequently the space above the fuel inthetank will be subjected to the engine suction.

An atmosphere vent pipe 6 extends from outside of the tank anddownwardly thru the tank to the bottom thereof. A fuel supply opening 7for the tank is normally closed by a cover plate 8.

In operation, when the engine is started, the suction in the carburetoror in the intake passageway is transmitted to the fuel tank thru theconnection 4 and a partial vacuum the tank. The air pressure in .thetank, being then less than that of the atmosphere, the fuel level in thevent pipe'6 will drop and when the artial vacuum becomes equal to thehead 0 fuel above the bottom of the vent is created in the space abovethe fuel level inpipe, all fuel in the vent pipe will have been forcedinto the main tank by the atmospheric pressure. Any tendency to create ahigher vacuum in the fuel tank space will be offset by the air flowinginto the space from the vent pipe and thru the fuel in the tank.

The suction in the carburetor is also communicated to the carburetorsupply pipe 2 and fuel is drawn up in this pipe to the carburetor, buton account of the balancing vacuum in the tank any tendency to increasethe vacuum by the drawing of fuel thru the pipe 2 will be compensatedfor by the passage" of air into the vacuum space thru the vent pipe 6and the depth of fuel in the tank will not influence the flow of fuel tothe carburetor but the conditions will always be thesame as tho thecarburetor were drawing its fuel from a level equal to that at the lowerend of the vent pipe 6. The advantage of my improved arrangement is thatthe action is" very rapid, for after only a few turns of the engine, thelevel or pressure condition will be adjusted so that the engine willalways be served under the same pressure condition. Another advantage ofmy arrangement is that it is not necessary to have thefuel tankabsolutely air tight, the only qualification being that the passagebetween the top of the tank and the carburetor or intake passageway belarge enough to draw off more air thru it than can leak into the tank.Still another advantage is due to the fact that the vacuum above thefuel will not be influenced by the formation of fuel vapors caused byheatin the fuel as all such vapors will be drawn 0 as they are should beof sufficient dimension to insure the creation of a sufiicient vacuumeffect in the fuel tank for efficient balancing purposes, care should betaken not to have the passage too large in order to prevent excessiveamounts of air being drawn thru the fuel in the tank which would tend toupset carburetion and also to draw off large quantities of fuel vapors.The passage 4 has a restricted portion X which acts to damp theinfluence of the manifold pulsations between the suction strokes of theengine. This assures maintenance of the proper degree of vacuum abovethe fuel when the throttle 5 is open, either partially or completely, sothat the effective fuel level in the tank remains constant and is notaffected by the pulsations between the engine strokes due to the inertiaof the fuel and the throttling action of the restriction. Thisrestriction X also prevents the flow of an excessively large volume ofair through the fuel supply with the resulting removal therefrom oflight ends.

I have shown an air vent or bleed 10 into the fuel supply pipe 2 whichvent is adjustable by means of a valve 11.

Having described my invention, I claim as follows:

1. In combination with an internal combustion engine and a carburetortherefor, a fuel tank, the actual fuel level in said tank being loweredby and in accordance with withdrawal of fuel therefrom, and means formaintaining a substantially constant effective fuel level in the tank,said means comprising a carburetor fuel supply tube extending from apoint adjacent the bottom of the tank, a vent tube having its lower endopening into the tank adjacent the bottom thereof and its upper end opento the atmosphere above the actual fuel level, and a suction tubeopening into the tank above the actual fuel level and communicating withthe fuel intake passageway of the engine.

2. In combination with an internal combustion engine and a carburetortherefor, a fuel tank, the actual fuel level in said tank being loweredby and in accordance with withdrawal of fuel therefrom, and means formaintaining a substantially constant effective fuel level in the tank,said means comprising a carburetor fuel supply tube extending from apoint adjacent the bottom of the tank, an air inlet tube opening intothe tank adjacent the bottom thereof. and means independent of said fuelsupply tube establishing communication between the space in the tankabove the fuel and the intake of the engine. whereby apartial vacuum iscreated and maintained: above the fuel by the direct action of theengine suction.

3. In combination with an internal combustion engine and a carburetortherefor, a fuel tank,.and means for compensating for lowering in theactual fuel level in the tank and for maintaining a substantiallyconstant effective fuel level therein, said means comprising acarburetor fuel supply tube extending from a point adjacent the bottomof the tank, an air inlet tube opening into the tank adjacent the bottomthereof, and a direct connection between the space in the tank above theactual fuel level therein and the intake passage of the engine.

4. In combination with an internal combustion engine and a carburetortherefor, a fuel tank, a carburetor fuel supply tube extending from apoint adjacent the bottom of the tank, said tank being below the portionof said tube within the carburetor, an air admission tube opening intothe tank adjacent the bottom thereof, and a suction tube comcunicatingwith the tank above the fuel therein and with the fuel intake passage tothe engine.

5. In combination with an internal combustion engine and a carburetortherefor, a fuel tank, the actual fuel level in said tank beingloweredby and in accordance with withdrawal of fuel therefrom, acarburetor fuel supply tube opening into the tank adjacent the bottomthereof, means for withdrawing the gases and vapors from the tank abovethe fuel and for maintaining a partial vacuum therein during operationof the engine, and an air admission tube opening into the tank adjacentthe bottom thereof.

6. In combination with an internal combustion engine and a carburetortherefor, a fuel tank, the actual fuel level in said tank being loweredby and in accordance with withdrawal of fuel therefrom, a carburetorfuel supply tube opening into the tank adjacent the bottom thereof,means for withdrawing the gases and vapors from the tank above the fueland for maintaining a partial vacuum therein during operation of the engine, said means acting to supply the withdrawn gases and vapors to theengine for consumption therein, and an air admission tube opening intothe tank adjacent the bottom thereof.

7 A method of supplying fuel to an internal combustion engine from asource of supply of fuel having a variable actual level, consisting inwithdrawing fuel from said source of supply and supplying the withdrawnfuel to the engine, creating and maintaining a partial vacuum above thebody of fuel constituting the source of supply by the suction effect ofthe engine, and admitting air to the space above the body of fuel whenthe value of the partial vacuum created exceeds the value of the head ofsaid fuel body.

8. A method of supplying fuel to an internal combustion engine from asource of supply of fuel having a variable actual level, consisting inwithdrawing fuel from said source of supply and supplying the Withdrawnfuel to the engine, withdrawing the gases and vapors from above the bodyof fuel constituting the source of supply and maintaining a partialvacuum above said bod and admitting air to the space above the b0 y offuel when the value of the partial vacuum created exceeds the value ofthe head of said fuel body.

In witness whereof, I hereunto subscribe my name this 15th day of July,1926.

ARTHUR W. POPE, J R.

